Where to learn advanced SQL coding

Where can I learn more advanced SQL programming to improve my ability in SQL?

I have reviewed the database AdventureWorks 2008 but I need more.

Read questions on sites like this one, Stackoverflow or other DBMS forums.

Then try to solve those problems.

Solving real world problems is still the best practice you can have.

StackExchange Database Administrators Q#14757, answer score: 21